Zabbix

/*

** Zabbix

** Copyright (C) 2001-2022 Zabbix SIA

**

** This program is free software; you can redistribute it and/or modify

** it under the terms of the GNU General Public License as published by

** the Free Software Foundation; either version 2 of the License, or

** (at your option) any later version.

**

** This program is distributed in the hope that it will be useful,

** but WITHOUT ANY WARRANTY; without even the implied warranty of

** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

** GNU General Public License for more details.

**

** You should have received a copy of the GNU General Public License

** along with this program; if not, write to the Free Software

** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

**/

​

​

/**

 * Amount of seconds for keep-alive interval.

 */

ZBX_BrowserTab.keep_alive_interval = 30;

​

/**

 * This object is representing a browser tab. Implements singleton pattern. It ensures there are only non-crashed tabs

 * in store.

 *

 * @param {ZBX_LocalStorage} store  A localStorage wrapper.

 */

function ZBX_BrowserTab(store) {

    if (ZBX_BrowserTab.instance) {

        return ZBX_BrowserTab.instance;

    }

​

    if (!(store instanceof ZBX_LocalStorage)) {

        throw 'Unmatched signature!';

    }

​

    ZBX_BrowserTab.instance = this;

​

    this.uid = (Math.random() % 9e6).toString(36).substr(2);

    this.store = store;

​

    var ctx_lastseen = this.store.readKey('tabs.lastseen', {});

    ctx_lastseen[this.uid] = Math.floor(+new Date / 1000);

​

    this.lastseen = ctx_lastseen;

​

    this.on_focus_cbs = [];

    this.on_blur_cbs = [];

    this.on_unload_cbs = [];

    this.on_crashed_cbs = [];

​

    this.bindEventHandlers();

    this.pushLastseen();

}

​

/**

 * @param {object} lastseen

 */

ZBX_BrowserTab.prototype.handlePushedLastseen = function(lastseen) {

    this.lastseen = lastseen;

};

​

/**

 * Checks and updates current lastseen object.

 */

ZBX_BrowserTab.prototype.handleKeepAliveTick = function() {

    this.lastseen[this.uid] = Math.floor(+new Date / 1000);

​

    this.findCrashedTabs().forEach(function(tabid) {

        delete this.lastseen[tabid];

        this.handleCrashed(tabid);

    }.bind(this));

​

    this.pushLastseen();

};

​

/**

 * Writes own ID in `store.tabs` object. Registers unload event to remove own ID from `store.tabs.lastseen`.

 * Registers focus event. Begins a loop to see if any tab of tabs has crashed.

 */

ZBX_BrowserTab.prototype.bindEventHandlers = function() {

    this.handleKeepAliveTick();

    setInterval(this.handleKeepAliveTick.bind(this), ZBX_BrowserTab.keep_alive_interval * 1000);

​

    window.addEventListener('beforeunload', this.handleBeforeUnload.bind(this));

    window.addEventListener('focus', this.handleFocus.bind(this));

    this.store.onKeyUpdate('tabs.lastseen', this.handlePushedLastseen.bind(this));